Electrochemical reduction of carbon dioxide at nanostructured SnO2/carbon aerogels: The effect of tin oxide content on the catalytic activity and formate selectivity

Electrochemical reduction of CO2 has been considered as a promising method for the production of value-added chemicals. In this work, the electrochemical reduction of CO2 to formate is carried out over novel carbon aerogel supported SnO2 nanocrystals prepared by a facile hydrothermal method. The as prepared materials exhibit good catalytic activity and high formate selectivity. It is found that the content of SnO2 plays an important role in the whole process, in which the formate is the exclusive product. At low SnO2 content the catalyst shows poor activity due to the lack of active ingredients, while at high Sn02 content it results in a dramatic decrease of the faradaic efficiency for the formate because of the blockage of part of active sites due to the agglomeration and poor conductivity of SnO2. It is also found that the optimized SnO2/CA-80 with 28.1 wt.% SnO2 leads to the best performance, offering a relatively high faradaic efficiency of 76% for the formate formation in 1.0 mol/L KHCO3 at -0.96 V (vs. RHE). Moreover, the above catalyst exhibits excellent stability during the control potential electrolysis for 12 h.